Re: [Help-glpk] Modelling Advice Request - Project Tasks

[Andrew Makhorin]

> I #39;m not sure I #39;m getting correct answers.  For the t65d11xx
> problem with gmpl code I got an objective
> value of 283,971 where the claim is that the best known value is
> 237,739.  I #39;m curious what you
> found for an objective value for this example.

My code finds 283971:

Reading LOP instance data from `t65d11xx.mat'...
GERMANY T65D11XXB
Digraph has 44 nodes
325 lines were read
Constructing initial basis...
Size of triangular part = 946
GLPK Simplex Optimizer, v4.43
946 rows, 1892 columns, 1892 non-zeros
*     0: obj =   1.157970000e+05  infeas =  0.000e+00 (0)
*   404: obj =   2.958730000e+05  infeas =  0.000e+00 (0)
OPTIMAL SOLUTION FOUND
GLPK Integer Optimizer, v4.43
946 rows, 1892 columns, 1892 non-zeros
1892 integer variables, all of which are binary
Integer optimization begins...
+   404: mip =     not found yet <=              +inf        (1; 0)
+   985: >>>>>   2.839710000e+05 <=   2.839710000e+05   0.0% (1; 0)
+   985: mip =   2.839710000e+05 <=     tree is empty   0.0% (0; 1)
INTEGER OPTIMAL SOLUTION FOUND

This is the correct answer; at least it is identical to the one
which is provided by Juenger et al:

  Value               : 283971
  Value + Diagonals   : 388229
  Degree of linearity : 0.830070
  Linear ordering     :  4 6 32 33 34 2 5 28 31 36 38 40 24 35 3 29 8
                         7 9 25 10 13 11 1 16 22 26 21 23 17 18 20 19
                         30 12 39 27 37 14 15 41 42 43 44
  Number of b&c nodes :              1
  Total time          :        0:02.42


Andrew Makhorin